Sewer

Sewer, conduit that carries wastewater from its source to a point of treatment and disposal. The wastewater may be domestic (sanitary) sewage, industrial sewage, storm runoff, or a mixture of the three. Large-diameter pipes or tunnels that carry a mixture of the three types of liquid wastes, called combined sewers, were commonly built in the 19th and early 20th centuries, and many are still in use. Today combined sewers are no longer built, however, because the large volumes of stormwater that must be carried during wet weather periods often exceed the capacity of sewage treatment systems. Instead, separate sewer systems are ... (100 of 457 words)